The present invention relates to the field of polymer chemistry. In particular, the present invention relates to composite polymer beads comprising at least one conductive polymer and methods for the preparation and use thereof.
Polymers containing conjugated unsaturated systems have been the focus of considerable attention due to their ability to conduct electricity. Doped polyacetylene, the first well-characterized and studied conducting polymer, exhibits conductivity values as high as 10.sup.5 S/cm (a value comparable to metal conductors). Various other conductive polymers have been identified and characterized, including polyphenylene vinylene (PPV) [Lenz, R. W. et al., J. Polym. Sci., Part A, Polym. Chem. Ed. 26:3241 (1988); Gagnon D. R. et al., Polymer. 28:567 (1987)], polydimethoxyphenylene vinylene (PDPV) [Antoun, S. et al., J. Polym. Sci., Part A. Polym. Chem. Ed. 26:1809 (1988)]and polyaniline (PA) [Cao, Y. et al., Polymer 30:2305 (1989)].
Organic polymer conductors display a wide range of conductivities, unlike common metal conductors. In addition, these polymeric materials have additional advantages relative to metal conductors which stem from their properties as polymers. Thus, typical conducting polymers exhibit superior strength-to-weight ratios. Moreover, the long term stability of the polymers themselves in some environments provides an additional advantage relative to metal conductors.
A significant obstacle which has heretofore limited the utilization of conducting polymers has been their lack of processibility. As the polymers are highly unsaturated, they tend to be both infusible and insoluble in most solvents. This makes shaping of the polymers by conventional techniques difficult. Moreover, the air stability of some conducting polymers after doping is also a problem. Thus, there is a need to develop processible conducting polymer compositions, as well as conducting polymer compositions which are more stable in air.
U.S. Pat. No. 4,636,430 to Moehwald describes composite materials consisting of a porous material and an electrically conductive polymer. The surfaces of the pores are first coated with a layer of an electrically conductive polymer obtained by treating polymer-forming monomers (generally, compounds from the class consisting of 5-membered heterocyclic compounds which possess a conjugated pi-electron system and contain nitrogen, sulfur or oxygen as heteroatoms) with an oxidizing agent in the presence of a conductive salt.
U.S. Pat. No. 4,724,053 to Jasne describes a method for the production of a processible electrically conductive organic polymer which comprises electropolymerizing an electropolymerizable monomer onto an anode in an electrolytic medium. The polymeric electrode has anionic surface character for affiliation with the cationic electropolymerized polymer on the anode; it is processed from a polymer material comprising an oxidatively polymerized polymer having cationic character in affiliation with a polymeric counterion particle having anionic surface character. The electropolymerized polymer and the anode on which it is formed are processed together by shaping them or size reducing them and dispersing the resultant size reduced material into a liquid vehicle for production of a coatable composition.
PCT published application WO 83/02954 (Ventrex Laboratories) describes solid polystyrenes and copolymers thereof with divinylbenzene which are derivatized on their surfaces with negatively charged sulfonate groups or with such groups followed by positively charged polyalkylamines. Adhesion proteins or other substances of like function, such as various unidentified serum proteins, are then covalently attached thereto, using 1-ethyl-3-(dimethylaminopropyl) carbodiimide or activation with glutaraldehyde followed by treatment with cyanoborohydride to reduce the unstable aminealdehyde addition product. The proteins are associated either with cellular anchorage dependence or immunogen anchorage. The coated materials are used as carriers for cell cultures or as substrata for solid state immunological reactions.
It is an object of the present invention to provide compositions comprising conducting polymers which are more processible and yet stable in air.
It is a further object of the present invention to provide methods for the preparation and use of conducting polymer compositions.